Fluorinated ketones and process for their preparation

ABSTRACT

Compounds of the formula: WHEREIN M, N and L may each be zero or from 1 to 99, the sum of M+N+L being zero or a number between 1 and 99, the ratio of N+L/M+1 being between zero and 2. Compounds prepared by heating a specified perfluorinated polyethers.

United States Patent Sianesi et al.

F LUORINATED KETONES AND PROCESS FOR THEIR PREPARATION Inventors: Dario Sianasi, Milan; Renzo Fontanelli, Rome; Gerardo Caporiccio,

Milan, all of Italy Assignee: Montecatini Edison S.p.A., Milan,

Italy Filed: March 31, 1970 Appl. No.: 24,371

Int. Cl. ..C07c 49/16, C076 49/ 18 Field of Search ..260/594 [151 3,683,027 [451 Aug. 8, 1972 [56] References Cited UNITED STATES PATENTS 2,988,537 6/1961 Wiley ..260/594 3,303,145 2/ 1967 Carlson ..260/586 R 3,513,203 6/1970 Sianesi et al ..260/594 3,564,059 2/1971 Sianesi et al ..260/594 Primary ExaminerDaniel D. Horwitz Attorney-Hubbell, Cohen & Stiefel ABSTRACT Compounds of the formula:

wherein M, N and L may each be zero or from 1 to 99, the sum of M+N+L being zero or a number between 1 and 99, the ratio of N+L/M+l being between zero and 2.

Compounds prepared by heating a specified perfluorinated polyethers.

14 Claims, No Drawings FLUORINATED KETONES AND PROCESS FOR THEIR PREPARATION CROSS-REFERENCE TO RELATED APPLICATION BACKGROUND OF INVENTION Field of the Invention The present invention relates to new chemical compounds and mixtures thereof, characterized in that they consist solely of carbon, fluorine and oxygen atoms, are

SUMMARY OF THE INVENTION The compounds and mixtures thereof of the present invention have a chemical structure corresponding to the general formula wherein M, N and L may be the same or different numbers and each may be zero or a whole number from 1 to 99, the sum of M+N+L being zero or a number between 1 and 99, the ratio of N+L/M+l being a number between zero and 2, and preferably between zero and 1; C l represents a perfluoroalkylene unit derived from the opening of the double bond of a hexafluoropropylene molecule; and the different perfiuoroalkylene units making up the molecules of the compounds have a random distribution along the polymer chain, these units being bound to each other through ether oxygen bonds.

Compounds of the formula (I) are obtained by heating specified perfluorinated polyethers as described subsequently.

DESCRIPTION OF THE PREFERRED I EMBODIMENTS By the process described hereinafter, the products of the invention are generally obtained in the form of mixtures of various compounds having the general formula these compounds having different values of the indexes M, N and L. From these mixtures the individual compounds, that is the chemical compounds characterized by a precise number for M, N and L, may be isolated by conventional separation methods such as, e.g., fractional distillation.

Examples of these new compounds include:

perfluoromethoxy-acetone, CF --CF (b.p. 8-l0 C.); perfluoro-4,7-dioxa--methyl-octanone-2,

(b.p. 80-82 C. at 755 mm Hg);

and higher homologues such as In addition, other pure compounds of series containing perfluoroalkylene units different from C F have been separated and are described and characterized in Example 8.

For many uses, however, the ketonic compounds of the invention can be used in admixture with each other, without any difficulty, e.g., in the form of distillation cuts characterized by desired average values of M, N and L, wherein M, N and L are not necessarily whole numbers. Such mixtures have a more or less restricted molecular weight distribution and may contain oligomers of different or isomeric structure.

The process for preparation of the products of the formula wherein M, N and L are as previously defined, and mixtures of said products, utilizes as the starting reactants perfluorinated polyethers of the general formula wherein P is a number between 1 and and is the same or greater than M+l; Q and R may be zero or the same or different numbers between 1 and 66, but Q and R are the same or greater than, respectively, the numbers N and L; the ratio of (Q+R)/P is a number between zero and 2, and preferably between zero and l; (O) is a peroxidic oxygen atom that is disposed between two perfluoroalkylenoxy units; S is an average composition number from zero to 10; and the ratio S/(P l-Ql-R) may be from zero to 0.1.

The process comprises heating a perfluorinated polyether of the foregoing formula (II) at a temperature of from about 100 to 350 C. under a pressure of from about atmospheric to about 30 atmospheres, or alternatively heating at a temperature of from about 0 to 300 C. when operating in the presence of. alkaline agents selected from the group consisting of organic tertiary nitrogen bases, oxides of electropositive metals and their salts of weak acids.

The starting materials, from which, by chemical transformation, are derived the fluorinated ketones of this invention, are obtained as the products of a photochemical reaction of oxygen with perfluoropropylene, as described in our U.S. Pat. application Ser. No. 650,257 filed on June 30, 1967, and now abandoned entitled Fluorinated Oxygen-Containing Products and Process for the Preparation Thereof, the contents of said application being incorporated herein by reference.

More particularly, in said application there is described a process based on the direct photochemical combination of liquid C l with oxygen, whereby there are obtained mixtures of compounds corresponding to the formulas According to the present invention, when compounds of the foregoing formulas are heated to a temperature of at least 100 C., and preferably above 100 C., COF is evolved along with the formation of new compounds with ketonic end groups, these new compounds being of the formula (I), namely,

wherein the value of M is equal to or less than P-l and wherein the peroxidic oxygen content is nil.

An example of this reaction is the transformation of perfluorol -methoxy-isopropyl fluoroformate,

into COP- perfluoromethoxyacetone, CF O CF COCF which occurs by heating the former to 200 -300 C.

A completely analogous reaction is obtained by heating the higher oligomers,

at temperatures higher than 100 C. and preferably between 200 and 350 C., with the formation of COF and oligomers having ketonic end groups, CF -O (C F O)BM -CF COCF Terminal ketonic groups are also obtained by thermal de-composition of polyethers having an analogous structure but with a terminal group have an average M value that may be lower than the value of P-l.

It should also be noted that for polyethers having terminal ketonic groups of the formula these products being obtainable by heating products of the formula up to 350 C., the integers M, N and L may be the same as the respective values of Pl, Q and R, or may be lower such as, e. g., P-2, 0-1, and R-l, respectively.

In general, the lower the number of peroxidic groups in the starting material and the lower the reaction temperature, the closer, in the ketonic reaction products, are the values of the indexes M, N and L to the corresponding values of P-l, Q and R of the starting materials. Conversely, the higher the number of peroxidic groups in the starting material and the higher the temperature at which the process is carried out, the more pronounced becomes the degradation of the molecular chain, so that the final ketonic compounds will be characterized by average composition indexes M, N and L that are markedly lower than the corresponding values of P-l, Q and R.

An advantageous variation in the process for the synthesis of fluorinated ketones of the formula from products having functional groups of the type comprises treating these products with an alkaline agent which does not contain active hydrogen atoms. Agents of this type include carbonates, oxides, oxalates, etc. of alkali and alkaline earth metals, and such other metals as, e.g., zinc, cadmium, aluminum, iron, etc.

Using this variation, it is sufficient to utilize a relatively short contact time at temperatures from lower than room temperature up to about 300 C., for the acid polyethers, either as they are or in solution, e.g., using a perhalogenated solvent, with the alkaline agent present in an amount not less than that required for complete neutralization. This is followed by distillation so as to obtain, as distillate, the polyethers containing a ketonic terminal group.

The reaction time in order to achieve a substantial conversion of the starting material into ketones varies within very wide limits. It is thus possible to consume more than 24 hours when operating by simple heating. In contrast, 20-30 minutes is generally sufiicient when the treatment is carried out in the presence of a suitable alkaline material.

The physical characteristics of the polyethers having a terminal ketonic group vary regularly by varying the values of M, N and L. The lower members, wherein M, N and L are zero, 1 or 2, are volatile low-boiling liquids, miscible in different organic solvents.

lubricants, for applications wherein high temperatures and/or strongly oxidative conditions are to be encountered, as heat-exchange liquids, inert fluids for carrying out chemical reactions, etc.

These fluorinated ketones are characterized by the presence in the IR absorption spectrum of a characteristic band in the position of 1803 cm. In the [R spectrum for these compounds, on the contrary, there are virtually absent those absorptions which would indicate the presence of other chemically reactive groups such as acid fluoride groups. More particularly, absorptions at 1884 cm (indicating the group CF COF), and at 1876 cml (indicating the group and around 1894 cml (indicating the groups and l 1.5 p.p.m., due to the groups -CF(CF )CF O-COF and respectively, which groups are present in the starting material, are, on the contrary, completely absent.

In the same NMR spectrum of fluorine, the presence in the chain of the group -OCF CF(CF )O- is indicated by the resonance of 5 fluorine atoms in the zone of +80 p.p.m. (from CFCl sand of 1 fluorine atom in the zone of +144 p.p.m. Resonance bands in the zones of +49 p.p.m. and +51 p.p.m. are due to the two fluorine atoms of the group -O-CF O-, whereas bands in the zone of +55 p.p.m. show the presence in the chain of repeating units (OCF with n 2 2. Resonance in the zone of 90 p.p.m. indicates the presence of the tertiary fluorine atom in the OCF(CF )O group.

In the following table, there are indicated the resonance bands of the various terminal groups that may be present in the starting material, and in part in the reaction product.

per-

There will now be described a preparation of the starting materials used in Examples 1 to 6 for the synthesis of ketonic compounds of the formula A cylindrical glass reactor having a diameter of 245 mm and a volume of 22 liters was assembled, in the center of which was inserted a quartz well containing a Hg vapor lamp of the Hanau TO 1200 type.

Into the reactor were also placed a dipping tube for the introduction of oxygen, a therrnometric well, and a gas outlet tube. The gas outlet tube was connected to a condenser cooled to -78 C., for condensing the volatile products and then recycling them back to the reactor. 25.7 Kg of liquid hexafluoropropylene at its boiling temperature (29 C.) were introduced into the reactor and molecular oxygen was circulated through it at a flow rate of about 1,000 l/h (liters per hour).

The photochemical reaction was continued for 17 hours, during which time the temperature of the reacting phase gradually rose to 10 C. Thereafter, unreacted perfluoropropylene and the volatile reaction products were distilled. From the latter, there were isolated 52 g of perfluoro-l-methoxyisopropyl fluoroformate,

boiling temp. 85 C. at 270 mm Hg; g of the homolog,

boiling temp. 82 C., at 35 mm Hg; boiling temp. and 25 g. of the higher homolog,

boiling temp. 93-5 C. at 20 mm Hg.

There were also obtained minor amounts of the following pure compounds:

CFa-OCFz-O-CF:CFOCOF ('3 F3 boiling temp. 85 C. at 760 mm Hg);

0Fwd-ci r-- --(JEFF?I---0)1-( o1 boiling temp135-l40 C. at 760 mm Hg);

boiling temp. 80-90 C. at 15 mm Hg);

boiling temp ll05 C. at 760 mm Hg); and

boiling temp. l45150 C., at 760 mm Hg).

The residual reaction product (17.1 Kg) had an elemental composition corresponding to the formula C 1 0, Iodometric analysis showed it to contain 0.37 active oxygen atoms per oxygen atoms.

Molecular weight determinations showed that the product had an average molecular weight of 2,400, with a ratio between and CF OCOF terminal groups of about 5. Molecules having a molecular weight between about 450 and about 10,000 were present.

NMR spectroscopic analysis indicated that the ratio P/Q+R) was about 12.

The following examples illustrate the present invention. All parts are by weight unless otherwise stated.

EXAMPLE 1 5 g of perfluoro- 1 -methoxy-isopropyl fluoroformate,

EXAMPLE 2 40 g of were slowly introduced at room temperature, under an anhydrous atmosphere, into a 250 cc glass flask provided with a reflux condenser cooled with running water and containing about 50 g. of anhydrous Na CO powder.

An exothermic reaction occurred with the evolution of gases which were collected in a vessel cooled with liquid nitrogen.

The contents of the flask were kept at a temperature of about 20 C. for a period of about 1 hour. Thereafter the product collected in the cooled vessel was subjected to fractional distillation, after removal of CO contained therein.

16.0 g of perfluoro-l-methoxyactone, b.p. 8l0 C., and 21 g of the starting fluoroformate were thus obtained. Essentially equivalent results were obtained by operating at room temperature under the same conditions, but using instead of Na CO an excess of KHCO or of ZnO or of A1 0 or of Ca0 or of pyridine as the promoter for the decomposition of the fluoroformate group to form the ketonic group.

EXAMPLE 3 60 g of were heated in a 200 cc autoclave for a period of 10 hours at a temperature of 250 C., and for a further 10 hours at a temperature of 300 C. At the end of this period no further increase of the internal pressure was observed. The contents of the autoclave were then subjected to fractional distillation in an anhydrous atmosphere, after removal of the COF contained therein.

35 g of perfluoro-4,7-dioxa-5-methyl-octanone-2,

having a boiling temperature of -82 C. at 755 mm Hg were thus obtained.

EXAMPLE 4 A sample of 50 g of was heated in a 200-cc steel autoclave for a period of 24 hours at a temperature of 320330 C. Thereafter, following cooling, there were removed the gaseous products consisting mainly of COF and, by fractional distillation of the residue, there were obtained 34 g of the compound having a boiling temperature of l40 C. at 755 mm Hg.

Another sample of 10 g of was introduced under an anhydrous atmosphere into a glass flask having a capacity of 50 cc and containing 10 g of K CO in the form of a dry powder. An exothermic reaction occurred with the evolution of a gas prevailingly consisting of CO while the temperature of the reacting phase was kept at about 20 C. by external cooling with running water.

boiling temp. l36l 39 C.

EXAMPLE 10 g of were introduced into a 100 cc glass flask provided with a reflux condenser. protected against atmospheric moisture and containing 20 g of anhydrous Na CO The mixture was kept for 2.5 hours at a temperature of l20-l 30 C. Thereafter, by fractional distillation under reduced pressure, there were obtained 6.2 g of having a boiling point between 170 and 180 C. at atmospheric pressure.

EXAMPLE 6 3.0 Kg of a product prepared as described above, which was the residue after distillation at 200 C. under atmospheric pressure, having a ratio of about 5 terminal groups with M-l-N+L having a value between 2 and about 60, with a number average molecular weight of about 2,500.

The ratio N+L)/M was about 0.08 ancl the ratio L/N was about 0. 1. Thus, no peroxidic oxygen was present.

The mixture of oligomers was distilled without reflux under a pressure of 0.1 mm Hg. in a temperature range between about 20 and 350 C., with a practically continuous distillation curve. There also was present a fraction corresponding to about percent by weight,

distillable only above 350 C., at 0.1 Hg. This residue appeared to have a number average molecular weight higher that 5,000.

EXAMPLE 7 The starting copolyether used in this example was obtained by the following process.

1,080 g of perfluoropropylene were introduced into an 800 cc. stainless steel autoclave provided with a pressure-proof coaxial inner wall of transparent quartz, with a dipping tube for the introduction of oxygen, and with a reflux condenser kept at a temperature of C.

From a cylinder provided with a pressure regulator, oxygen was introduced through the dipping tube until a pressure of 5 atmospheres was reached.

By adjusting a discharge valve in the condenser line, an oxygen flow of 40 l/h was maintained, keeping constant the pressure inside the reactor.

A high pressure U.V. lamp of the Hanau T.Q. 81 type was introduced into the quartz well and the reactor was cooled to +10 to 12 C.

Irradiation was thus carried out for 2 hours. At the end of this time the pressure was released and unreacted C F was removed together with perfluoropropylene epoxide, bubbling these products through an alkaline washing bath.

842 g of gaseous products were obtained consisting of unreacted C 1 along with 10 percent of epoxide. The residue in the reactor consisted of 180 g of oily polyether products having an elemental composition corresponding to the formula CF O and an average molecular weight of 1,200.

By iodometric analysis a peroxidic oxygen content of 1.01 g per g of product was determined.

By N.M.R. analysis this product appeared to consist of polyether chains containing groups of the CF O type together with -CF CF(CF )O-- groups in the molar ratio of about 1:2.

-CF(CF )O units in an amount corresponding to one/tenth of the CF O-units were also present in the chain.

The terminal groups consisted of: CF O- in the forms of CF OCF -CF (CF )O-, CF O--CF O and CF O-CF(CF )-O, and also of acid terminals preponderantly of the type O--CF -CF(CF OCOF, and OCF(CF )CF OCOF, the first of which was prevalent.

100 g of this product were heated to 300 C. for 24 hours in a 0.2-liter oscillating autoclave. The pressure rose due to to formation of gases which, at the end of the reaction, were discharged and appeared to consist prevailingly of COF and CF COF.

After the addition of 20 g of anhydrous K CO the residual product (84 g) was distilled between 40 C. under atmospheric pressure and 200 C. at 0.2 mm Hg.

75 g of a neutral product were obtained, having an average molecular weight of about 1,100. The elemental composition corresponded to the formula 1.99 0.4e-

lodometric analysis showed that peroxidic oxygen was absent.

N.M.R. analysis showed that the product contained terminal groups CF O-. These groups were of the three types already described along with the terminal EXAMPLE 8 Using the apparatus described in Example 7, a run was carried out by operating under an oxygen pressure of 3 atmospheres while keeping the temperature of the reactor at 50 to 8 C.

1,065 g of perfluoropropylene were charged. At the end of the reaction, there resulted 705 g of unreacted perfluoropropylene, 13 g of perfluoropropylene epoxide, and 300 g of oily copolyether products having an elemental composition corresponding to the formula CF and a number average molecular weight of 3,000.

By iodometric analysis a peroxidic oxygen content of 1.30 g per 100 g of product was O-By NMR analysis this product appeared to consist of polyether chains containing groups of the CF type together with groups of the CF(CF )CF O type in a molar ratio of about 1:4.

CF(CF )O units were also present in amounts corresponding to 1:10 of the CF O-- units. The terminal groups were the same as those of the products described in the preceding example.

Using the same procedure as described above, 1,000 g of obtained polyether product were treated, in a 1.5- liter glass flask provided with agitator and reflux condenser, with 250 g of anhydrous Na CO and heated to a temperature of 150 C. for 5 hours.

Therefore, the mixture was filtered and 800 g of an oily product were thus obtained. Elemental analysis showed that the product corresponded to the formula CF O From iodometric analysis it appeared that it did not contain peroxidic oxygen.

The product was subjected to fractional distillation.

From the fractions, samples of the following compounds or oligomers of the same compositions and of isometric structures were obtained. The compounds were separated in the pure state, their boiling temperatures at 760 mm Hg were determined, and the results The undistilled residue consisted of 550 g of a product having a number average molecular weight of about 3400 and an elemental composition corresponding to the formula CFLO0 39.

The product did not contain peroxidic oxygen.

NMR analysis showed it to have CF O tenninal groups in the three forms CF OCF CF(CF CF OCF O and CF OCF(CF )O in the ratio of l0:3:0.3, and a ketonic terminal group OCF COCF this latter being present with respect to the sum of the other terminals, in a ratio of 1:1.

The total ratios between CF O, C F O and CF(CF )O units corresponded to those found in the starting product.

To this product the average formula was attributed.

Variations can, of course, be made without departing from the spirit of our invention.

Having thus described our invention, what we desire to secure and claim by Letters Patent is:

What is claimed is:

l. A process for the preparation of products of the formula wherein M, L and N are zero or a whole number from 1 to 99, and mixtures thereof, the different perfluoroalkylenoxy units having a random distribution along the polymer chain, comprising heating a perfluorinated polyether of the formula wherein P is a whole number between 1 and and is the same or higher than M+1, Q and R are each zero or the same or different whole numbers between 1 and 66 and are the same or higher than N and L, respectively, the ratio of (Q-l-R)/P is a number between zero and 2, (0) is a peroxidic oxygen atom that is disposed between two perfluoroalkylenoxy units, S is a number from zero to 10 and the ratio S/(P+Ql-R) is from zero to 0.1, said heating being at a temperature of from about 100 C. to about 350 C. when done in the absence of an alkaline agent and being at a temperature of from about to 300 C. when done in the presence of an alkaline agent selected from the group consisting of organic tertiary nitrogen bases, oxides of electropositive metals and electropositive metal salts of weak acids.

2. The process of claim 1 wherein the ratio (Q+R)/P is between zero and l.

3. The process of claim 1 carried out at a pressure of from about one to about 30 atmospheres.

4. The process of claim 1, wherein the alkaline agent is an oxide or carbonate of an alkali metal, an alkaline earth metal, cadmium, zinc, aluminum or iron.

5. The process of claim 1, wherein the alkaline agent is pyridine.

6. A perfluorinated ketone and mixtures of ketones having the formula wherein M, N and L are zero or a whole number from 1 to 99, the sum of M+N+L is zero or a whole number between 1 and 99, the ratio N+L/M+l is a number between zero and 2, and the different perfluoroalkyleneoxy units have a random distribution along the polymer chain. 7

7. The product of claim 6, wherein the ratio N+L/M+is between zero and l.

8. The product of claim 6 having the structure CF OCF COCF 9. The product of claim 6 having the structure 10. The product of claim 6 having the structure 11. The product of claim 6 having the structure CF OCF OCF COCF 12. The product of claim 6 having the structure 13. The product of claim 6 having the structure 14. A perfluorinated ketone having the formula wherein X is selected from the group consisting of F d CF N M h t f 1 t 98 th iim of N-l-li /l ils a i l u lril r tii e r i i (iii 99,and th Patent No 3,683,027 I Dated August 8, 1972 Inventor) Darlo S1anesi et a1.

It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Columri 12, lines 16 and 17, the formula should appear as shown below:

CF 0 (CF CF-O) (CF -0 c1=-o1 -cF -CO-CF 1s3190c 0.2

3 I 2 l 2 2 l' 2 3 (3P3 CF3 Signed and sealed this 3rd day of September 1974.

(SEAL) Attest: v

MCCOY M. GIBSON; JR. Y Y c. MARSHALL DANN Attesting Officer Commissioner of Patents FORM po'wso uscoMM-Dc 60376-P69 US. GOVERNMENT PRINTING OFFICE: I969 0-366-334. 

2. The process of claim 1 wherein the ratio (Q+R)/P is between zero and
 1. 3. The process of claim 1 carried out at a pressure of from about one to about 30 atmospheres.
 4. The process of claim 1, wherein the alkaline agent is an oxide or carbonate of an alkali metal, an alkaline earth metal, cadmium, zinc, aluminum or iron.
 5. The process of claim 1, wherein the alkaline agent is pyridine.
 6. A perfluorinated ketone and mixtures of ketones having the formula wherein M, N and L are zero or a whole number from 1 to 99, the sum of M+N+L is zero or a whole number between 1 and 99, the ratio N+L/M+1 is a number between zero and 2, and the different perfluoroalkyleneoxy units have a random distribution along the polymer chain.
 7. The product of claim 6, wherein the ratio N+L/M+1 is between zero and
 1. 8. The product of claim 6 having the structure CF3- O- CF2-CO-CF3.
 9. The product of claim 6 having the structure
 10. The product of claim 6 having the structure
 11. The product of claim 6 having the structure CF3- O- CF2- O-CF2-CO-CF3.
 12. The product of claim 6 having the structure
 13. The product of claim 6 having the structure
 14. A perfluorinated ketone having the formula wherein X is selected from the group consisting of F and CF3, N and M are each an integer from 1 to 98, the sum of N+M is a number between 2 and 99, and the ratio N/M is a number between 0.01 and 2, the different perfluoroalkyleneoxy units having a random distribution along the polymer chain. 